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DC/DC Controller: LT3761

December 3, 2012
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3761Linear Technology announces the LT3761, a 60 V DC/DC controller designed to operate as a constant-current source and constant-voltage regulator. Its internal PWM dimming generator makes it ideal for driving high current LEDs, but it also has features making it suitable for charging batteries and super-capacitors.
The LT3761's 4.5V to 60V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting. The LT3761 uses an external N-channel MOSFET and can drive up to fifteen 1A white LEDs from a nominal 12V input, delivering in excess of 50 watts. It incorporates a high-side current sense, enabling its use in boost mode, buck mode, buck-boost mode or SEPIC topologies.


The LT3761 can deliver efficiencies of over 94% in the boost topology, eliminating the need for external heat sinking. A frequency adjust pin permits the user to program the frequency between 100kHz and 1MHz, optimizing efficiency while minimizing external component size and cost. Combined with a thermally enhanced MSOP-16 package, the LT3761 offers a very compact high power LED driver solution.


The LT3761 has an internal PWM generator that delivers dimming ratios as high as 50:1 or it can utilize an external PWM signal, delivering dimming ratios of up to 3,000:1. For less demanding dimming requirements, the CTRL pin can be used to offer a 10:1 analog dimming range. Its fixed frequency, current-mode architecture offers stable operation over a wide range of supply and output voltages. Output short-circuit protection and open LED protection enhance system reliability. The LT3761's ground-referenced voltage FB pin serves as the input for several LED protection features and also makes it possible for the converter to operate as a constant-voltage source for charging applications.


The LT3761EMSE is available in a thermally enhanced MSOP-16 package. Pricing starts at $3.45 each. An extended temperature version, or I grade, the LT3761IMSE, is also available, priced starting at $3.86 each.  Finally a high temperature or H grade option, the LT3761HMSE is also available, starting at $4.11 each. All pricing is based on 1,000-piece quantities and all versions are available from stock.

Summary of Features: LT3761:

  • 3,000:1 True Color PWM™ Dimming for LEDs
  • Wide VIN Range: 4.5V to 60V
  • Rail-to-Rail Current Sense Range:
  • 0V to 80V
  • Programmable PWM Dimming Signal Generator
  • Constant Current (±3%) &
  • Constant-Voltage (±2%) Regulation
  • Analog Dimming
  • Drives LEDs in Boost, SEPIC, Inverting, Buck Mode, Buck-Boost Mode, or Flyback Configuration
  • Output Short-Circuit Protected Boost
  • Open LED Protection & Reporting
  • Adjustable Switching Frequency:  100kHz to 1MHz
  • Programmable VIN UVLO with Hysteresis
  • C/10 Indication for Battery Chargers
  • Low Shutdown Current: <1µA
  • Thermally Enhanced 16-Lead MSOP Package

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